Method of refining cracked oil by using metallic soaps



Patented Apr. 18, 1939 UNITED STATES PATENT .QFFlCE METHOD OF REFININGCRACKED OIL BY USING METALLIC SOAPS No Drawing.

Original application August 11,

1934, Serial No. 739,500. Divided and this application April 13, 1937,Serial No. 136,686

1 Claim.

The present invention is a division of our copending application SerialNo. 739,500, filed August 11, 1934, and relates to a method of refiningcracked oil, by adding to cracked oil at or 5 below the ordinarytemperature one or more of copper, lead, zinc and iron salts of fattyacids in solid state, or dissolved in gasoline, petroleum, benzol,toluol, xylols, or turpentine, or in a mixture of two or more of saidsolvents, whereby 1 not only all the offensive odor compounds and otherimpurities contained in the cracked oil will be combined with the metalor metals in dissolved state and be precipitated as insoluble saltscontaining the offensive odor compounds, but also even the disagreeableodor compounds which react only with great diificulty be adsorbed andprecipitated at the same time.

The object thereof is to bring all of principal offensive odorsubstances such as thioalcohols contained in cracked oil into intimatecontact at a comparatively low temperature with metallic salts oforganic acids soluble in cracked oil, whereby same will react upon eachother directly by double decomposition and be precipitated as .25insoluble salts, and at the same time to produce compounds, which reactonly with difiiculty with ordinary refining agents, such as for instancedisulphides, deposited by the astringent and adsorptive actions of theseinsoluble salts at the moment of their formation, thus removing allsubstances which cause disagreeable odor completely from the cracked oilwithout involving any operation which would be detrimental to volatileoil, such as agitation, stirring, etc.

This invention relates to a method of refining the cracked oil producedby cracking processes of petroleum oils, tars manufactured from coal andshale, and other organic matters and is adapted mainly for removingcompletely the offensive odor substances contained in cracked oil whileat the same time increasing the stability of the product.

The offensive odor substances in cracked oil are chiefly di-sulphides,unsaturated organic 5 compounds, and thioalcohols, particularly the lowboiling thioalcohols. These substances even in the slightest quantitygive an offensive odor to volatile oil. For instance, ethyl thioalcoholwill give a disagreeable odor to gasoline even 50 when in concentrationsof A or A by weight.

Thioalcohol gives an offensive smell which decreases with an increase inits molecular weight, but even the crystallizable higher members of 55thioalcohols give a bad odor, and thioalcohols have a tendency to reducetheir reactive powers gradually with an increase in molecular Weight.

In cracked oil, the quantity of disulphide originally present is onlyvery small, but as most of same is produced by the oxidation of thethioalcohols, its quantity consequently increases gradually with lapseof time after the manufacture of the cracked oil. This compound alsogives a burning odor to cracked oil. It reacts only with extremedifiiculty with ordinary refining agents for cracked oil, andconsequently the disulphide is difficult to remove therefrom.

Some unsaturated organic compounds in cracked oil are very unstable. Ifisolated, they will for the most part polymerize at once, but if dilutedwith gasoline, same will become comparatively more stable. Suchcompounds give a disagreeable odor to cracked oil by their oxidationproducts. However, they may be removed easily by treatment withsulphuric acid.

Now, according to the present method which is the result of the study ofthe constituents and properties of many such disagreeable odorsubstances, same may be removed completely.

The known methods all employ refining agents insoluble in the matter tobe purified, so that even by violent agitation it is difiicult to causeintimate contact of a refining agent with the .matter to 'be purifiedthe difficulty rising when the differences in specific gravityincreases. Therefore, only a portion, but not the Whole, of thesedisagreeable odor substances are removed and complete removal of saidsubstances cannot be realized. In refining operations, the

oxidation of thioalcohols in accelerated with the;

violence of agitation in the atmosphere, and therefore such agitationnot only causes the thioalcohols to remain as disulphides, but alsocauses loss of gasoline due to volatilization, and thus causes adecrease in yield of the product.

The inventor has isolated various kinds of thioalcohols from cracked oiland manufactured various kinds of disulphides therefrom, and thenstudied their reactions with various kinds of metals and metallic saltsof organic and inorganic acids, and studied their various propertiesincluding solubility, stability, etc. Also, he has studied the ease andspeed of formation of metallic salts from the solutions of thioalcoholsand disulphides in petroleum hydrocarbons, and studied the behavior ofthese salts in petroleum hydrocarbons. Thus, by applying the results ofthese studies to cracked oil, he has ascertained the most favorableconditions, with regard to the refining of cracked oil, and hisdiscovery is as follows:

1. One or mixture of copper, lead, zinc and iron salts of fatty acids,such as oleic acid, are easily soluble in gasoline, petroleum oil,benzol, toluol, xylols, turpentine, etc., and when kept as concentratedsolutions, same do not change their qualities.

2. If a solution of metallic salts of these organic acids is added togasoline or petroleum oils containing thioalcohols, same dispersesthroughout the latter spontaneously, mixes with it and reacts with thethioalcohols by double decomposition even at the ordinary roomtemperatures or below such temperatures, thereby, depositing metallicsalts of thioalcohols. Thus, in this man ner it is possible to removesaid thioalcohols completely from the oil.

As to the reactions taking place in this process, the inventor hasstudied same fully with regard to oleic acid. It is illustrated by thefollowing equation of the reaction of propyl thioalcohol with oleicsoap:

CU.(SC3H7)2 produced here is also converted into disulphide and cupricsalt of propyl thioalcohol as soon as it is produced.

3. Disulphide produced here is mostly adsorbed into a metallic salt ofthioalcohol the instant it is produced and is deposited with the salt ifthe product is allowed to settle spontaneously without stirring, andpresents the same appearance as if this refining reaction had occurredaccording to the Equation I alone.

4. It is necessary that the reaction between the metallic salt oforganic acid and the thioalcohol should proceed slowly. Thus, after thecompletion of the reaction and after deposition of metallic salt ofthioalcohol and disulphide, the supernatant oil should be filteredgently through a filter bed of fullers earth, and thus these offensiveodor substances may be completely separated from the oil to be purified.

5. The refined cracked oil may be subjected to steam distillationdirectly. After the gasoline fraction-is distilled, the residual oil isstirred with an alkali solution, and thus the fatty acid may berecovered as alkali soap from the oil.

When the result of the above'study was applied to the refining ofcracked oil, it was possible to produce cracked gasoline entirely freefrom thioalcohols and the offensive odor caused by the disulfides.

The following are a few examples of refining of cracked oil for the,preparation of cracked gasoline:

Add 0.5% (by volume) of 20% caustic soda solution to kilolitres of thecracked oil produced from Dubbs cracking plant and agitate it to removesulphuretted hydrogen, organic acids and other reactive substances fromthe cracked oil. This pre-treatment minimizes the amount of metallicsalt of organic acid required. Next, after Washing with enough water tocompletely remove Next, subject the filtered oil to steam distillationin a steam still and distill off the gasoline fraction. Put the gasolinefraction in a continuous treating apparatus and wash it with sulphuricacid, alkali and water by turns. The finished gasoline thus produced hasan excellent quality free from disagreeable odor.

Thus, it may be possible to obtain gasoline of superior quality which isnot only free from disagreeable odor, but also has a very highstability.

The invention above stated has the following advantages:

1. As a refining agent is easily brought into very intimate contact withthe substance to be refined, it can react with the whole of offensiveodor compounds in the cracked oil.

2. It is possible to not only remove the disulphides produced duringreaction in the refining, but also to remove disulphides originallycontained in the matter to be refined by astringent and adsorptiveactions.

3. For the above reason, oflensive odor substances can be removedcompletely from cracked oil.

4. As the matter to be purified is not stirred or agitated, it ispossible to prevent the oxidation of any thioalcohols, and alsovaporization losses of the volatile portion of the matter to be refinedare minimized.

5. The recovery of the refining agent is simple.

We claim:

The method of refining cracked oil, which consists in dissolvingoilsoluble heavy metallic soap of oleic acid in a volatile organicsolvent which will disperse homogeneously in cracked oil; pouring thesolution thus obtained slowly into cracked oil to effect dispersionnaturally and homogeneously at room temperature in the cracked oilwhereby same will react with the intermingling mercaptans andprecipitate same by double decomposition as insoluble metallic salts;separating the precipitate; and distilling the remaining liquor toseparate it from the organic solvent.

MASAKICHI MIZUTA. TEIJI YOSHIMURA.

